The process is more effective in hydrated state where under conditions of high humidity, hydrolysis and denaturation occur, thus lower heat input is required. Under dry state, oxidative changes take place, and higher heat input is required.
S OF DIFFERENT STERILISATION
METHODS AND IN PROCESS
KOSARAJU SAI VIVEK
DEPARTMENT OF PHARMACEUTICS
Jss college of pharmacy
1. WHAT IS STERILIZATION
2. METHODS OF STERILIZATION
3. MERITS, DEMERITS
ANDAPPLICATIONS OF DIFFERENT
METHODS OF STERILIZATION
4. PHARMACEUTICAL IMPORTANCE OF
5. PHARMACEUTICAL IN PROCESS
WHAT IS STERILIZATION:
Sterilization can be defined as any process that
effectively kills or eliminates transmissible agents
(such as fungi, bacteria, viruses and prions) from a
surface, equipment, foods, medications, or
biological culture medium.
METHODS OF STERILIZATION
The various methods of sterilization are:
1. Physical Method
a. Thermal (Heat) methods
b. Radiation method
c. Filtration method
2. Chemical Method
a. Gaseous method
1. HEAT STERILIZATION:
Heat sterilization is the most widely used and
reliable method of sterilization, involving
destruction of enzymes and other essential cell
This method of sterilization can be applied only to
the THERMO STABLE PRODUCTS, but it can be
used for MOISTURE-SENSITIVE MATERIALS.
i) Dry Heat (160-1800˚C) Sterilization for
thermo stable products
ii) moist heat (121-1340 ˚C) sterilization is
used for moisture- resistant materials.
The efficiency with which heat is able to
inactivate microorganisms is dependent upon
i) the degree of heat, the exposure time and
ii) the presence of water.
The action of heat will be due to induction of
lethal chemical events mediated through the
action of water and oxygen.
In the presence of water much lower
temperature time exposures are required to kill
microbe than in the absence of water.
THERMAL (HEAT) METHODS
Thermal methods includes:
i) Dry Heat Sterilization
2. Red heat
4. Hot air oven
ii) Moist Heat Sterilization
1.Dry saturated steam – Autoclaving
2. Boiling water/ steam at
3. Hot water below boiling point
Dry Heat Sterilization
It employs higher temperatures in the range of
160-180˚C and requires exposures time up to
2 hours, depending upon the temperature
The benefit of dry heat includes good
penetrability and non-corrosive nature which
makes it applicable for sterilizing glass wares
and metal surgical instruments. It is also used
for sterilizing non-aqueous thermo stable
liquids and thermo stable powders.
Dry heat destroys bacterial endotoxins (or
pyrogens) which are difficult to eliminate by
other means and this property makes it
applicable for sterilizing glass bottles which
are to be filled aseptically
Moist Heat Sterilization
Moist heat sterilization involves the use of
steam in the range of 121-134˚C. Steam under
pressure is used to generate high temperature
needed for sterilization. Saturated steam acts
as an effective sterilizing agent.
Autoclaves use pressurized steam to destroy
microorganisms, and are the most dependable
systems available for the decontamination of
laboratory waste and the sterilization of
laboratory glassware, media, and reagents.
For efficient heat transfer, steam must flush
the air out of the autoclave chamber.
Generally the conditions employed are
Temperature upto121-134˚C for 15-20 min under
15 lbs pressure,based on type of metiral used.
Many types of radiation are used for
sterilization like electromagnetic radiation (e.g.
gamma rays and UV light), particulate
radiation (e.g. accelerated electrons).The
major target for these radiation is microbial
Radiation sterilization with high energy gamma
rays or accelerated electrons has proven to be
a useful method for the industrial sterilization
of heat sensitive products.
Radiation sterilization is generally applied to
articles in the dry state; including surgical
instruments, sutures, prostheses, unit dose
ointments, plastic syringes and dry
UV light, with its much lower energy, and poor
penetrability finds uses in the sterilization of
air, for surface sterilization of aseptic work
areas, for treatment of manufacturing grade
water, but is not suitable for sterilization of
pharmaceutical dosage forms.
Filtration process does not destroy but
removes the microorganisms. It is used for
both the clarification and sterilization of liquids
and gases as it is capable of preventing the
passage of both viable and non viable
The major mechanisms of filtration are
sieving, adsorption and trapping within the
matrix of the filter material.
Sterilizing grade filters are used in the
treatment of heat sensitive injections and
ophthalmic solutions, biological products and
air and other gases for supply to aseptic areas.
They are also used in industry as part of the
venting systems on
fermentors, centrifuges, autoclaves and freeze
driers. Membrane filters are used for sterility
There are two types of filters used in filtration
(a) Depth filters:
(b) Membrane filters: These are porous
membrane about 0.1 mm thick, made of
cellulose acetate, cellulose
nitrate, polycarbonate, and polyvinylidene
fluoride, or some other synthetic material.
The chemically reactive gases such as
formaldehyde, (methanol, H.CHO) and
ethylene oxide (CH2)2O possess biocidal
activity. Ethylene oxide is a colorless,
odorless, and flammable gas.
The mechanism of antimicrobial action of the
two gases is assumed to be through
alkylations of sulphydryl, amino, hydroxyl and
carboxyl groups on proteins and amino groups
of nucleic acids.
The concentration ranges (weight of gas per
unit chamber volume) are usually in range of
800- 1200 mg/L for ethylene oxide and 15-100
mg/L for formaldehyde with operating
temperatures of 45-63°C and 70-75°C
Both of these gases being alkylating agents
are potentially mutagenic and carcinogenic.
They also produce acute toxicity including
irritation of the skin, conjunctiva and nasal
MERITS, DEMERITS AND
DIFFERENT METHODS OF
MERITS DEMERITS APPLICATIONS
Dry heat is applicable
for sterilizing glass
wares and metal
and moist heat is
the most dependable
laboratory waste and
the sterilization of
media, and reagents.
MERITS DEMERITS APPLICATIONS
ability of gases.
It is a useful
method for the
changes occur in
of water occurs.
Ethylene oxide gas has
been used widely to
Radiation sterilization is
generally applied to articles
in the dry state; including
sutures, prostheses, unit
dose ointments, plastics
MERITS DEMERITS APPLICATIONS
Does not destroy
but removes the
It is used for both
the clarification and
liquids and gases as
it is capable of
passage of both
viable and non
and non viable
This method is Sterilizing
grade filters are used in
the treatment of heat
sensitive injections and
biological products and
air and other gases for
supply to aseptic areas
Pharmaceutical Importance of
• Moist heat sterilization is the most efficient biocidal
agent. In the pharmaceutical industry it is used for:
Surgical dressings, Sheets, Surgical and diagnostic
equipment, Containers, Closures, Aqueous injections,
Ophthalmic preparations and Irrigation fluids etc.
• Dry heat sterilization can only be used for thermo
stable, moisture sensitive or moisture impermeable
pharmaceutical and medicinal. These include products
like; Dry powdered drugs, Suspensions of drug in non
aqueous solvents, Oils, fats waxes, soft hard paraffin
silicone, Oily injections, implants, ophthalmic
ointments and ointment bases etc.
• Gaseous sterilization is used for sterilizing
thermolabile substances like; hormones,
proteins, various heat sensitive drugs etc.
• U.V light is perhaps the most lethal
component in ordinary sunlight used in
sanitation of garments or utensils.
• Gamma-rays from Cobalt 60 are used to
sterilize antibiotic, hormones, sutures, plastics
and catheters etc.
Filtration sterilizations are used in the
treatment of Heat sensitive injections and
ophthalmic solutions, biological products, air
and other gases for supply to aseptic areas.
They are also used in industry as part of the
venting systems on fermentors, centrifuges,
autoclaves and freeze driers. Membrane filters
are used for sterility testing.
In-process controls (IPC) are checks that are
carried out before the manufacturing process
The function of in-process controls is
monitoring and – if necessary – adaptation of
the manufacturing process in order to comply
with the specifications. This may include
control of equipment and environment, too.
The In-Process Quality Control system lays
emphasis on the responsibility of
manufacturers processors in ensuring
consistency in quality during all stages of
production by adopting quality control drills
and exercising control on raw materials and
bought-out components, manufacturing
process, packing and final testing.
Not less than 90.0 % and not more than110.0
% of the labeled claim of drug. Relative
standard deviation (RSD) is not more than 5.0
HARDNESS – Stokes (Monsanto), Strong
Cobb, Pfizer, Erweka, Hebelein or Schleuniger
tester, units: kg/sq inch of kg/sq cm,
FRIABILITY –Roche , limit less tan 1%
UNIFORMITY OF CONTAINER CONTENTS.
Tablets comply with the test for contents of
packaged dosage forms.
Select a sample of 10 containers and count the
number of capsules, pessaries, suppositories or
tablets in each container. The average number of
the contents in the 10 containers is not less than
the labelled amount and the number in any single
container is not less than 98 per cent and not more
than 102 per cent of the labelled amount.
If this requirements is not met, count the
number of the contents in 10 additional
containers. The average number in the 20
containers is not less than the labelled amount,
and the number in not more than 1 of the 20
containers is less than 98 per cent or more
than102 per cent of the labelled amount.
1 Particulate matter
2 Uniformity of content
3 Extractable volume
6 Uniformity of weight
7 Clarity of solution
Parenteral preparations including solutions
constituted from sterile solids are expected to be
free from particles of approximately 50 μm or
more that can be observed byinspection with the
After transferring the contents of the container or
containers to be tested to the membrane add an
inoculum of a small number of viable micro-organisms
(not more than 100 CFU) to the final portion of sterile
diluent used to rinse the filter.
After filtration, aseptically remove the membrane(s)
from the holder, transfer the whole membrane or cut it
aseptically into 2 equal parts. Transfer one half to each
of two suitable media.
Direct Inoculation. After transferring the contents of
the container or containers to be tested to the culture
medium add an inoculum of a small number of viable
micro-organisms (not more than 100 CFU) to the
Quantity in each container Minimum quantity to be
Less than 1 ml Total contents of a
40 ml or more but less than
100 ml 20 ml
1 ml or more but less than
40 ml Half the
contents of a container
100 ml or more 10 per cent of the contents
container but not less than
Incubate the inoculated media for not less
than 14 days.
• Observe the cultures several times during the incubation
period. Observe the containers of media periodically
during the 14 days of incubation. If the test specimen is
positive before 14 days of incubation, further incubation
is not necessary.
• For products terminally sterilised by a validated moist
heat process, incubate the test specimen for not less
than 7 days.
• Observation and Interpretation of Results
If no evidence of microbial growth is found, the
preparation under examination complies with the test for
sterility. If evidence of microbial growth is found, the
preparation under examination does not comply with the
The test involves measurement of the rise in body temperature of
rabbits following the intravenous injection of a sterile solution of
the substance under examination. It is designed for products that
can be tolerated by the test rabbit in a dose not exceeding 10 ml
per kg injected intravenously within a period of not more than 10
Use healthy, adult rabbits of either sex, preferably of the same variety, weighing
not less than 1.5 kg
Carry out the test using a group of three rabbits.
PREPARATION OF THE SAMPLE:
Dissolve the substance under examination in, or dilute with, pyrogen-free saline
solution orother solution prescribed in the monograph. Warm the liquid under
examination to approximately 38.5º before injection.
INTERPRETATION OF RESULTS:
If the sum of the responses of the group of three
rabbits does not exceed 1.4º and if the response of
any individual rabbit is less than 0.6º, the
preparation under examination passes the test. If
the response of any rabbit is 0.6º or more, or if the
sum of the response of the three rabbits exceeds
1.4º, continue the test using five other rabbits.
If not more than three of the eight rabbits show
individual responses of 0.6º or more, and if the sum
of responses of the group of eight rabbits does not
exceed 3.7º, the preparation under examination
passes the test
Uniformity of content
Determine the content of active ingredient(s) of each of 10
containers taken at random, using the method given in the
monograph or by any other suitable analytical method of
equivalent accuracy and precision.
The preparation under examination complies with the test if
the individual values thus obtained are all between 85 and
115 per cent of the average value.
The preparation under examination fails to comply with the
test if more than one individual value is outside the limits
85 to 115 per cent of the average value or if any one
individual value is outside the limits 75 to 125 per cent of
the average value
If one individual value is outside the limits 85 to
115 per cent but within the limits 75 to 125 per
cent of the average value, repeat the
determination using another 20 containers taken
The preparation under examination complies with
the test if in the total sample of 30 containers not
more than one individual value is outside the limits
85 to 115 per cent and none is outside the limits
75 to 125 per cent of the average value
Clarity of solution
Constitute the injection as directed on the label.
a) The solid dissolves completely, leaving no visible
residueas undissolved matter.
b) The constituted injection is not significantly less
than an equal volume of the diluent or of water for
injections contained in a similar container and
examined in the same manner.
A LEAKERS TEST :
It is a useful method for evaluating the efficiency
of the sealing process.
The test consists of immersing completely the
sterile sealed ampoules in an aqueous dye
bath (0.5 to 1.0% of methylene blue) within a
Negative pressure of 27 inches Hg or more is
created, a tiny drop of dye solution can penetrate
an opening of an incompletely sealed ampoule.
the colored ampoule are sorted out during
washing and 100% inspection that follows after.